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AI That Keeps Working After You Teach It Once — Codex Skills Basics

Learn how to teach Codex a task you used to explain repeatedly, just once, using a Codex skill. Here are 14 practical skills you can use directly in Codex in the ChatGPT app.

1 learners are taking this course

Level Beginner

Course period Unlimited

codex
codex
ChatGPT
ChatGPT
AI Agent
AI Agent
prompt engineering
prompt engineering
codex
codex
ChatGPT
ChatGPT
AI Agent
AI Agent
prompt engineering
prompt engineering

What you will gain after the course

  • Explain what a skill is and how it differs from a prompt

  • Create a skill card (name · description · body) yourself and place it in the Codex skills folder.

  • Write one sentence explaining how to make skills get called automatically—including the order of steps to follow when they aren’t called.

  • Format · Examples · What Not to Do · Ask and Wait: Making Skills Smarter with Four Ingredients

  • Know the Four Ways AI Makes Mistakes and Prevent Them with Checklists and Calculation Programs

  • Customize 13 practical skills—such as meeting minutes, replies, expense summaries, review responses, work schedules, and quote comparisons—to fit my work.

  • How to chain skills, share the same game with your team, and protect your personal information

Are you collecting good prompts in a notepad?

Do you find yourself repeating the same explanation every time you ask AI to do something? “Our store is a snack bar, use a friendly tone, keep replies to 3–5 lines, don’t promise compensation…” Many people collect prompts that worked well in a notepad, then look them up and paste them in every time. But this approach has its limitations. You have to search for them each time, and as you make small edits, the versions start to diverge. Template files have to be uploaded separately, and when you share them with employees, each person ends up modifying them differently.

A skill is a way to teach this explanation just once. Put the order forms, templates, must-dos, and don'ts in a single folder, and the AI will retrieve and use them when needed. You don't write a single line of code. A skill is a written recipe for work.

Same Request, Different Result — Without and With Skills

We start by showing you the finished product.

The very first lesson shows you the results right away. All I did was paste in three delivery app reviews and say, "Write replies"—yet the AI pulled up the review-reply skill, read the store information file, separated the praise and complaints in each review, and wrote different replies for each one in the store’s tone. It does not make promises about rewards that haven’t been predetermined. Every results screen shown in the course is from an actual run.

Actual screen showing the review reply skill being called in Codex in the ChatGPT app

4 parts on principles + 3 parts on practical cases

In Parts 1–4, you’ll learn the principles that endure: what a skill is, how to create your first skill, the one-sentence description that gets a skill called automatically, the four ingredients—format, examples, things not to do, and questions to ask—and the four ways AI makes mistakes, along with how to prevent them using a checklist. These principles remain the same even when the app interface changes.

Prompts and skills are different in the following ways.

Parts 5–7 cover practical examples. We’ll look at everyday skills anyone can use (meeting minutes, replies in my tone of voice, card expense summaries, one-page summaries), small business skills (review replies, menu descriptions, a week’s promotional posts, part-timer schedules, month-end wrap-ups), and professional work skills (checking VAT documents, responding to payroll inquiries, reviewing contracts, comparing quotes), one by one, including how to adapt them to your own work. You can also start with the section closest to your work.

14 skills covered in this course

Claude Version · Codex Version — You only need to take one

This course is based on Codex. There is a separate Claude version of the course covering the same content with a different tool. You do not need to take both courses.

  • What is the same in both courses: The lessons on principles (Parts 1–4) and practical examples (Parts 5–9)—about 85% of the total consists of the same videos. This is because both tools use the same format of skill files. In some of the practical lessons, screens from both tools appear together.

  • What differs between the two courses: previewing the finished product first (0–2), the three hands-on lessons in Part 2, and the installation appendix — about 30 minutes.

  • The course materials are also the same. The 14 skills used in the course include both a zip file for the Claude app and a folder version for Codex.

So just choose the course for the tool you’re currently using. If you’ve already taken the Claude course, you don’t need to purchase this one.

If you use both tools or your team uses a mix of the two, enroll in both courses through the “AI Claude · Codex Skills Fundamentals Roadmap” and receive a 50% discount with the roadmap coupon.

We show it honestly—even the parts that didn’t go well.

This course does not show only the scenes that went well. We’ll show you as-is a skill that still wouldn’t reliably improve even after revising the instructions twice, a reply that made up the sentence “We make broth every morning,” which wasn’t in the store’s information, and a scene where it tried to open the calendar on its own even though it was only told to write a reply. We’ll look together at how each was fixed with a single line in the skill. We’ll also show the results of testing it again with the same reviews after adding a checklist, exactly as the numbers came out. However, since the number of tests is limited, we won’t say it will “always” work.

Four Ways AI Gets Things Wrong

AI handles the preparation; people make the judgments.

Tax, labor, and legal skills only create drafts up to the point before expert review. They are designed to prevent tax calculations, payroll calculations, and judgments about the advantages, disadvantages, or legality of contracts. AI’s role is to gather and organize information and identify questions to ask; people and experts handle the judgments and decisions. As a rule, customer personal information should not be entered into AI.

Be sure to check this.

  • What you need: A paid ChatGPT plan (Plus or higher) and a Windows or Mac computer. No coding is required.

  • The store (Hanip Bunsik), people (such as Manager Kim Min-ji of the flower shop Bomnal), and companies featured in the course are all fictional, and the AI response screens are examples to aid understanding. Actual responses may vary from time to time.

  • The narration is an AI voice trained on CEO Lee Sang-soo’s own voice.

  • At the end of the lecture, the instructor will show you on screen only the fully developed skills used in practice (preliminary closing and tax adjustment statement analysis). These two skills are not included in the course materials.

Class materials

  • 9 lecture PDF volumes — The complete lecture screens (slides), with a copyright notice on every page

  • 14 skills for the course — Folder version (for Claude Code and Codex) and a zip file for uploading to the Claude app

  • 140 Ready-to-Use Prompts — Prompts you can copy and use by changing only the [bracketed text]

  • Find Your Work Skills Worksheet — For Part 1 and Part 9 Exercises

Once you download the course materials, cancellations are no longer possible. The course materials may not be distributed or shared without authorization.

Recommended for
these people

Who is this course right for?

  • Office workers who repeat meeting minutes, email replies, and report summaries every day

  • Small-business owners who handle review replies, promotional posts, part-time worker schedules, and month-end wrap-up all by themselves

  • Business owners and staff in charge of comparing quotes, reviewing contracts, and gathering tax documents

  • People who keep good prompts for ChatGPT or Claude in a notepad and paste them in every time

  • For those who don’t know how to code but want to move on to the stage of 'delegating' tasks to AI

Hello
This is sangsu09160857

I’m Lee Sang-soo, CEO of Lbiz Partners. For over 20 years, I have provided management consulting to small and medium-sized businesses, delivering training and advisory services to around 1,000 companies. More recently, I have worked with over 500 graduates through AI utilization training. I am the author of “Successful Companies Clearly Have a Special Reason” and “Management Consulting Is Over,” and I hold international lead auditor qualifications for three ISO standards. I make it easy for frontline salespeople and business owners to learn practical ways to use AI that they can put to work starting tomorrow.

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Curriculum

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39 lectures ∙ (3hr 34min)

Course Materials:

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